Make it easier to switch repos and branches when building images
Make it easier to switch repos and branches when building images

By default, Citrix-internal repos are used in the '%' target. This can
be overridden with

  make CTTRIX= <target>

Likewise, the default branch is trunk-ring3. This can be overridden with

  make BRANCH=<branch> <target>

Signed-off-by: Christian Lindig <4f88b50bc9dba63c9a7d9e208d4b3ac6f1a52800@citrix.com>

lindig/xs-shipyard